Rear Hubs

Mountain Bike Rear Hub Buyer's Guide

Rear hubs are the only part of a mountain bike where constant noise is not a nuisance. That melody does, however, serve a purpose. What you hear is the sound of a ratchet mechanism's pawls clicking off of the hub's engagement points. Modern mountain bikes use rear hubs equipped with a freewheel, upon which the cassette is mounted. The wheel itself spins on bearings within the hub around an axle. Rear hubs are available in a variety of sizes, designs and colors to excel in any mountain bike application.

Types

There are three types of mountain bike rear hubs - singlespeed, freewheel and internally geared. Singlespeed specific rear hubs are built to accommodate only one gear. This is either done by use of a driver or a modified freewheel. Standard mountain bike hubs use a freewheel design, which has a ratcheting body attached to the driveside of the hub onto which the cassette mounts. Internally geared rear hubs, although rare, are also an option. This design does not require a derailleur, instead using a system of springs and gears housed within the hub to provide variable resistance.

Sizes

Rear hubs are sized according to the diameter and length of the rear axle (measured in millimeters). This measurement depends on the frame design, so be sure to find out what size rear hub your bike requires. The available mountain bike sizes are: 165x12, 157x12, 150x12, 142x12,135x10 and 135x5mm.

Materials

Rear hub bodies and freewheel bodies are made from aluminum because it is both light and stiff. Some hubs use a carbon fiber middle section to save weight. Axles come in steel, aluminum or titanium. Bearings are available in steel or ceramic options.

Things To Look For

Before shopping around for a hub, be sure to know what size of axle your frame requires, and whether or not you require an internally geared model. Once that is sorted out, there are a few criteria that may help choosing the best model for you: intended use, bearing type and rotor compatibility. A hub's general design depends on the type of riding it was intended for. Downhill and freeride hubs are built to withstand the abusive nature of their disciplines. Cross-country hubs shed some unnecessary material and weight because of the more docile application. All-mountain rear hubs fall somewhere in between, balancing strength and lightness in their designs.

Hubs also use different qualities and types of bearings. Some manufacturers choose loose pack bearings, while others prefer sealed designs.

Finally, there are two types of disc brake rotor standards, Centerlock and International Standard (six bolt), each requiring a dedicated hub design. Be sure to choose a model that is compatible with your brake rotor.

How Much To Spend

Mountain bike rear hubs range in price from $35 to $500.

Models in the $35-$100 range are available mostly in 135x10 or 135x5mm, with some 150x12 downhill/freeride options as well. They generally use loose bearings, are available in both Centerlock and International Standard disc options.

Moving up to the $100-$250 range, hubs are available in every size and style. Components at this price range begin to use more precise machining techniques and more sophisticated designs to improve performance and reduce weight.

Hubs in the $300-$500 range are top of the line parts designed for competitive riders seeking ultimate performance and minimal weight. These often have the most points of engagement, meaning they'll ratchet less before catching and propelling you forward.

Product Reviews

Before buying, be sure to do your research and read product reviews. Reviews are a great way to find out specifics about a particular model, user impressions, and things to watch out for. After you've purchased a product and had enough time to thoroughly test it, we encourage you to leave a review for other people to see when they are researching bikes and parts on the web.

We hope you've found this information to be helpful. If you have a question that isn't answered in this guide, our mountain bike forums are a great place to get advice from knowledgeable riders. Your local bike shop is also a great resource.